This invention relates, in general, to electronic components, and more particularly, to semiconductor components.
Differential capacitive pressure sensors typically have a fixed electrode, a single pressure-movable diaphragm electrode, and a small gap separating the two electrodes wherein the gap is exposed to the pressure sensing environment. During sensor operation, a change in pressure deflects the diaphragm electrode and modifies the size of the gap between the two electrodes, which changes the capacitance measured between the two electrodes.
However, these capacitive pressure sensors are highly susceptible to particulate contamination because dust and other particulates can easily become trapped in the gap. The particulates come from ambient during sensor fabrication, assembly, and from the gas or liquid pressure sensing media during sensor operation. The particulates prevent the diaphragm electrode from moving properly in response to changes in pressure.
Furthermore, when the pressure sensing environment is ambient, the prior art capacitive pressure sensors are also susceptible to humidity and other forms of moisture in the ambient because the moisture changes the dielectric constant of the air between the two electrodes. Therefore, humidity variations change the capacitance measured by the sensor even when the ambient pressure remains constant.
Moreover, some differential capacitive pressure sensors also require large support substrates that waste space and increase the cost of the sensors.
Accordingly, a need exists for smaller and cost-effective pressure sensors that are not susceptible to particulates or moisture from the pressure sensing environments.